Method of making glass fibers



July 30, 1963 A. c. DUCATI 3,099,548

METHOD OF' MAKING GLASS FIBERS Original Filed May 29, 1958 5 Sheets-Sheet 1 25x fj f 4Z l je Smm Y' j,

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,00P/10N 0 C. 00677/ July 30, 1963 A. c. DUCATI v3,099,543

METHOD oF MAKING GLASS FIBERS original Filed May 29, 1958 5 s sheets-sheet 2 FIG. 4.

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R. 7 E O WC E e W a MW gv.. B 6 6 United States Patent O 3,099,548 METHOD F MAKING GLASS FIBERS Adriano C. Ducati, Newport Beach, Calif., assignor to Ilasmadyne Corporation, Santa Ana, Calif., a corporation of California Continuation of abandoned application Ser. No. 738,887, May 29, 1958. This application Dec. 29, 1961, Ser. No. 163,332

1 Claim. (Cl. 65-5) This invention relates to a method of making vitreous iirbers. More particularly, the invention relates to the blowing or drawing of ber-forming material into tine threads or laments iby the ruse of electrical plasma-jet torch means. 'I'his application is a continuation of patent application Serial No. 738,887, now abandoned, filed May 29, 1958, for Method of Making Glass fibers.

The manufacture of fibers from vitreous material has previously heen penformed i-n a number of ways, including spinning on a rotating drum, and blowing or drawing `by means of a blast of air, steam or heated gas. A highly impontant consideration in all of these methods is the maintenance of a suiciently high temperature at the point of blowing or drawing. A further important consideration or factor relates Ito the making of vitreous bers having diameters suiiiciently small to increase the strength and other properties of the resulting manufactured products. `One substantial difficulty previously encountered with relation to the :forming of vitreous material into tine threads or filaments was that the rate off production was decreased to an uneconomical level. Thus, in order to manufacture lange weights of fibers -having extremely small diameters, it is necessary that the rate of drawing of the molten 'glass be extremely high. A highly important limitation of prior-art methods was that -it was impossible or impractical to make fibers out of vitreous substances, including zirconia and a number of other refractories, having high melting points.

In view of the above factors characteristic of the manufacture of vitreous bers, and particularly ii'bers having small diameters, it is an object of the present invention to provide an eflicient and economical rnethod'fo-r manufacturing small-diameter vitreous iifbers at a high rate of production.

A hunther object is to provide a method of manufacturing extremely small-diameter iibers by performing blowing or drawing at very high temperatures and velocities.

A further object is to provide a practical method for forming fibers out of substances having high melting points.

A further object is to provide a method of manufacturing vitreous iibers lfrom vitreous substances in various conditions, includ-ing molten, rod and powder.

'Ihese and other objects and advantages of the present invention will be more fully set forth in the lfollowing specification and claim, considered in connection with the attached drawings to which they relate.

In the drawings:

FIGURE l is a schematic view, partly in elevation and partly in vertical section, illustrating the use of electrical plasma-jet torches in drawing molten vitreous material out of a vat and converting the molten material into vitreous fibers;

FIGURE 2 is an enlarged section taken upon line 2-2 of FIGURE l;

FIGURE 3 is a section on line 3--3 of FIGURE 2, illustrating the tangential passage means for introducing constricting gas into the plasma-jet torch;

FIGURE 4 is a schematic view illustrating the use of plasma-jet torches in converting a vitreous rod into iilaments or iibers;

3,099,548 Patented July 30, 1963 FIGURE 5 illustrates schematically the passing of molten vitreous substance through a plasma-jet torch to result in the formation of fibers;

FIGURE 6 is an enlarged section taken on line 6-6 of FIGURE 5;

FIGURE 7 is a sectional view illustrating the feeding of a glass rod through a plasma-jet torch;

FIGURE 7A is a view, partly in elevation and partly in section, showing the feeding of vitreous substance into the jet in a chamber formed .forwardly of the nozzle electrode;

FIGURE 8 illustrates an embodiment in which a plasma-jet torch is employed to blow vitreous substance from the surface of a pool thereof; and

FIGURE `9 illustrates an embodiment in which a plasma jet is passed through the vortex in a pool of whirling vitreous material in liquid condition.

Refer-ring iirst to the embodiment of FIGURES 1-3, a vat or feeder lll, having a suitable liner 11, is shown as iilled with molten :glass or other vitreous substance 12. The vat 10 and liner 11 converge downwardly, and liner 11 is provided with a downwardly extending tubular nipple 13 the lower end of which is located a substantial distance below vat 1t); Suitable auxiliary heating means, such as means to pass an electric heating current through at least the lower pontion of liner 11 and nipple 13, may be provided tto maintain a downward ilow of molten substance 12 at suitable temperature.

The vat 10, which is lformed of a suitable refractory material, is shown as having a lower are or flange portion 14 adapted -t-o mount one or more plasma-jet torches 16, there being two such torches illustrated in the drawings. The torches 16 are so mounted that their plasma jets 17 converge toward the stream of molten glass iiowing out the lower end of nipple 13, so that a blast of hot plasma is provide-d in the same :general direction as the flow of molten xglass. The plasma serves to draw glass out of the nipple and convert the same into iine threads or laments. The plasma jets 17 have a high temperature, for example several thousand degrees centigrade, and a very high velocity in the sonic range. This combination of high temperature and velocity has the effect of forming fine `.glass iilaments or fibers at a high rate of production.

Referring particularly to FIGURES 2 and 3, each plasma-jet torch 16 is illustrated to comprise a generally disc-shaped nozzle electrode 18 having a nozzle opening 19 at its axis or center, the nozzle opening being protected by a refractory sleeve or insert 21 which may be formed of a metal such as tungsten. A disc-shaped back electrode 22 is provided in spaced coaxial relationship relative to nozzle electrode 18, being electrically separated from a skirt portion 23 of the nozzle electrode by means of suitable insulators 24. The central or arcing portion of the back electrode is also protected by a suitable electrically-conductive refractory substance, such as the tungsten insert shown at 26.

An annular arc chamber 27 is formed between nozzle electrode 18 and back electrode 22, and coaxially therewith, for the purpose of receiving constricting gas introduced through a tangential passage shown at 28 in FIG- URE 3. Constricting gas is introduced into passage 28 from a suitable hose 29 leading to a gas pressure source, not shown, and enters the chamber 27 through an inlet 31. The pressure and velocity of the constricting gas are such that the gas whirls in the arc chamber 27 to form a vortex between the back electrode insert 26 and the nozzle opening 19. Because of the electrical insulating characteristics of the whirling gas, an electric arc struck between the refractory metal 26 and 21 is constricted to the vortex, so that the temperature of the arc is greatly elevated. The electrical plasma jet 17 is thus generated and flows at high velocity out the nozzle opening 19 as shown in the drawings.

Electric current is conducted to the nozzle 18 through a lead 32 (FIGURES 1 and 3), and to the back electrode 22 through a lead 33 (FIGURE 2). Leads 32 and 33 are connected to a suitable source, not shown, of electric current. The source should be a D.C. source and be capable of delivering hundreds of amperes. The voltage need not be great, however, for example 100 volts. In order to increase the life of the electrodes, the constricting gas introduced through hose 29 and passage 28 should be an inert gas such as argon, for example.

The absolute pressure of the gas entering through tangential inlet 31 should be at least 1.6 times the absolute ambient pressure. Ihe spacing between back electrode 22 and nozzle electrode 18, that is to say the distance between the adjacent surfaces of inserts 21 and 26, should be about l to 2 times the diameter of nozzle opening 19, and should not be more than 4 times such diameter. The diameter or arc chamber 27 should be at least 2 times the diameter of nozzle opening 19, and the cross-sectional area of inlet 31 should be less than the cross-sectional area of nozzle opening 19. These and other factors relative to the plasma-jet torch 16 are set forth in detail in patent application Serial Number 697,279, now abandoned, filed November 18, 1957, for Plasma Stream Apparatus and Methods, inventors Gabriel M. Giannini and Adriano C. Ducati. Said application constitutes `a continuation-in-part of application Serial Number 649,461, now abandoned, filed March 29, 1957, by the same inventors for Plasma Stream Apparatus and Methods.

The electrodes 18 and 22 are suitably cooled, for example by means of a series-connected water cooling circuit comprising an inlet passage 34 through which water flows to a chamber 36 provided behind back electrode 22 in a body or stem element 37. The Water then flows out a passage 38 to a hose 39 and thus to an annular chamber 241 Aformed around insert 21 in nozzle electrode 18. From chamber 41, the water flows out a hose 42 leading to a suitable drain. This construction is similar to the one described in the above-cited patent applications, particularly with reference to FIGURE 3 thereof.

To summarize the method of FIGURES 1-3, gas is introduced through passage 28 (FIGURE 3) and whirls in arc chamber 27 around an electric arc struck between inserts 26 and 21. The arc is thus constricted by the gas to the vortex therein, and a certain proportion of the gas enters the are to provide electrical plasma which streams through the nozzle opening 19 at high temperature and velocity. The jet of plasma from one or more torches 16 is directed at an angle toward the lower end portion of nipple 13, as shown in FIGURE 1, producing the effect of drawing molten glass from the vat and converting the glass into filaments or fibers. Such filaments or fibers may be collected in a suitable hopper or other suitable means, such as is schematically represented in {FIG- URE 5.

Embodilnent of FIGURE 4 FIGURE 4 shows a pair of plasma-jet torches 16 which may ber identical to those described with reference lto FIGURES 2 and 3. Torches 16 (one or more) are suitably mounted and are so directed that their plasma -jets 17 converge against opposite sides of a vitreous rod '44 at the same region or area. The rod 44 is thus melted, .and the `molten material is blown into threads or filaments lindicated at 46. The rod 44 is suitably driven and guided, such as by feed rolls 47 and a guide or bushing 48.

:It 'is to be understood that the use of the term rod is not intended to denote that the element v44 must be relatively rigid and discontinuous. Instead, the rod 44 may -be a long thread wound on a feed roll. Thus, the torches 16 convert the thread into bers having much smaller diameters than that of the thread.

4 Emboament of FIGURES 5 and 6 FIGURES 5 and 6 show an embodiment in which molten glass is fed through a torch 16a which Iis similar to the one described with reference to FIGURES 2 and 3. Except as will be specifically stated, the torch 16a is identical to the one 16 previously described, and the representation thereof has been provided with similar reference numerals. The body 37 and back electrode 22 of FIGURE 2 are combined into a single back electrode unit 49, and the water-cooling means for the back electrode are eliminated. An axial passage 51 is provided in electrode 49 and communicates with a central opening in the tungsten insert 26a. The diameter of nozzle opening 19a should be substantially increased in order to prevent or minimize the deposition of glass on the insert 21a.

Molten glass, or other vitreous material, is fed into the outer end of passage 51 from a suitable vat 52 having a bushing or nipple S3 disposed closely adjacent the outer end of electrode 49. It is to be understood that the bushing 53 may be suitably lined, and may be suitably heated such as by electric resistance heating, in order to maintain a suitable flow of glass at the desired temperature. The glass ilow through passage 51 is maintained due to the fact that electrode unit 49 is heated by the electric arc, there being no water cooling illustrated. Alternatively, however, the unit 49 may be suitably water cooled, particularly at the insert 26a, and suitable means provided to maintain the walls of passage 51 sufliciently hot to insure flow of glass at .the desired temperature. The glass fibers emanating from the torch 16a enter a hopper schematically represented at 54, tromwhich they are conducted by means of a suitable conveyor belt 56.

To summarize the method of FIGURES 5 and 6, the molten glass from vat 52 is caused to ilow through passage 51, from which it enters the base portion of the electric arc struck between inserts 26a and 21a. The whirling gas in chamber 27 constricts this arc yand also constricts the glass flowing downwardly out of passage 51, Iso that the glass is maintained away from the inner wall of nozzle insert 21a. Because of the high velocity and temperature of the plasma jet owing from electrode 49 and out nozzle opening 21a, the molten glass is converted into filaments or threads represented lat 57.

Embodment of FIGURE 7 FIGURE 7 illustrates a plasma-jet torch 16h which is identical to the torch 16 described with relation to FIG- URES 2 [and 3, except that an axial passage 58 is provided in body 37b and back electrode 22h. The back electrode 22b is formed with a hollow `stem 59 which enters a counterbore in bodyr 37b, the result being that the passage 58 Iis @continued through stem 59 and through the central portion of insert 26b. It `is to be understood that the electrica'l conductor 33 (FIGURE 2) is connected to a portion of the body 37b other than the center or axis. Except as specifically stated, the torch 16b is identical to the one 16 previously described.

In the method of FIGURE 7, a rod 60 of glass or other vitreous substance is introduced through passage v58 and axially `into the arc chamber 27. .This rod is converted into viscous or melted condition by the heat, and bers are drawn therefrom because of the high velocity of the plasma owing through .the nozzle opening.

Instead of introducing the vitreous substance in rod form as illustrated, it is within the `scope of the invention to introduce the vitreous substance in powder form through the passage 58 (or other passage) into the plasma jet, so that the powder is converted to tillaments by the heat and velocity of the jet. The powder may be introduced along with a suitable carrier, such as an inert gas canrier.

Embodment of FIGURE 7A FIGURE 7A shows a plasma-jet torch 16e which is identical to the torch 16 described with reference to FIG- URES 2 and 3. In this embodiment, an additional watercooled disc `60a is mounted forwardly of the nozzle electrode 1S, being separated therefrom by insulation 60h. Disc 60a has 1a central opening, pnotected by refractory metal, through which the plasma jet passes after emanating from the nozzle opening in electrode 18. Gas may be introduced into the space between disc 60a and nozzle 18, for cooling, protective, carrier or other purposes.

Glass is introduced through suitable openings into the plasma jet in the region between nozzle 118 and disc 60a, for example in the `form of the rods `60. The glass may also be introduced in molten or powder form. One advantage of this embodiment is that the glass may enter the jet iat right angles. Furthermore, the `arrangement is unitary Iand highly efficient.

It is also within the scope of the invention to shoot two plasma jets out of an arc chamber in `diarnetrically opposite directions through coaxial openings in the nozzle and back electrodes. Glass i-s then introduced into both jets, such as by feeding into the arc chamber, to provide very efficient fiber formation.

Embodment of FIGURE 8 In the embodiment of FIGURE 8, a plasma-jet torch 16 is employed and may be identical to the one described with reference to FIGURES 2 and 3. The plasma jet 17 emanating from the torch 16 is employed to blow the meniscus 61 off the upper end of an upwardly-liowing stream `62 of molten glass, so that threads or filaments 63 are formed. 'The stream 62 flows through a refractory tube 64 from a vat or furnace 65, it being understood that the level of the surface :(not shown) of the molten glass 66 in the vat or furnace may be `approximately the same \as the elevation of the meniscus 61 so that a continuous flow is provided.

Embodment of FIGURE 9 In this embodiment, the torch 16 yof FIGURES 2 and 3 is again employed, and is mounted coaxially with a centrifugal vat 68 having an annular or cylindrical chamber 69. The upper disc-shaped wall of vfat 68 is formed with a central opening 70` intol which (the plasma jet 17 is directed. The lower disc-shaped wall of the vat 68 has a central opening the Wall of which is a cylindrical surface disposed radially outwardly from the lower end of jet 17. An insert disc 71 is suitably mounted in such opening, yand has a central outlet 72 through which the jet 17 *(and contained glass bers) emanate. Disc 71 does not rotate with vat `68. Glass is fed, in molten or powder form, through a passage 73 leading to the stationary insert 71 and thus into the chamber 69.

The vat `69 is rotated `at a substantial velocity, and ooaxially with the jet 17, by a motor 'and drive means schematically represented at 74 and 75, respectively. The glass lin vat l69 thus forms a vortex through which the jet 17 passes at high velocity. The jet draws a certain proportion of the glass with it in the form Eof the fibers or filaments indicated at the lower portion of FIG- URE 9. The process may be a continuous one, with the rate of introduction of glass through passage '73 being the same as the rate of withdrawal of glass through opening 72 due -to the action of plasma jet 17.

it is to be understood that suitable means may be provided to heat the glass in chamber 69, and suitable liner means, etc., may be employed in -a manner known to the art. This applies also to the embodiment of FIG- URE 8 and to all embodiments. The stationary insert '7'1 may be suitably mounted in any manner, land suitable sealing means may be provided to prevent leakage of glass between the outer cylindrical surface of stationary insert 71 and the adjacent inner cylindrical surface of the lower Wall of rotating vat 68.

The pre-sent method is vapplicable to substantially any substance capable of bei-ng blown for drawn into relatively fine fibers at high temperatures. Thus, the terms glass, vitreous substance, etc., as employed in this specification and in the claim, are defined to include not only true glass but also quartz and a number of refractories such as zirconia and alumina. It is an important feature of the present method that a number of these refractory substances may be converted into fibers from which cloth and other products may be made.

The power input to the plasma-jet torch, the degree of arc constriction and other factors, are so regulated that the jet temperature is substantially higher than the melting point of the substance being converted into fibers. The jet is thus operated normally in the range of about 2,000 degrees C. to 5,000 degrees C., or even higher.

lVarious embodiments of the present invention, in `addition to what has been illustrated and described in detail, may be employed without departing from the scope of the accompanying claim.

I claim:

A method of manufacturing small-diameter threads or fibers of vitreous material, which comprises providing a centrifugal vat having inlet and outlet openings in the axis thereof, rotating said vat about said axis, introducing vitreous material into said vat and maintaining the vitreous material in said vat in molten condition whereby a vortex is formed therein along the axis between said inlet and outlet openings, and passing a jet of high-temperature high-velocity electrical plasma axially into said inlet opening and through said vortex in said molten material to thereby cause flow of fibers or filaments out -said outlet opening.

References Cited in the file of this patent UNITED STATES PATENTS 1,133,508 Schoop Mar. 30, 1915 2,338,473 Von Pazsiczky Jan. 4, 1944 2,489,242 Slayter et al Nov. 22, 1949 2,616,843 Sheer et al. Nov. 4, 1952 2,768,279 Rava Oct. 23, 1956 2,770,708 :Briggs Nov. 13, 1956 2,795,819 Lezberg et al June 18, 1957 2,806,124 Gage Sept. 10, 1957 2,859,560 Wald et al Nov. 11, 1958 2,925,620 Karlovitz et al. Feb. 23, 1960 3,015,127 Stalego Jan. 2, 1962 

